Electronic device with first and second contact pads and related methods

ABSTRACT

An electronic device may include leads, an IC having first and second bond pads, and an encapsulation material adjacent the leads and the IC so the leads extend to a bottom surface of the encapsulation material defining first contact pads. The electronic device may include bond wires between the first bond pads and corresponding ones of the leads, and conductors extending from corresponding ones of the second bond pads to the bottom surface of the encapsulation material defining second contact pads.

TECHNICAL FIELD

The present disclosure relates to the field of electronic devices, and, more particularly, to integrated circuits and related methods.

BACKGROUND

In electronic devices with integrated circuits (ICs), the ICs are typically mounted onto circuit boards. In order to electrically couple connections between the circuit board and the IC, the IC is typically “packaged.” The IC packaging usually provides a small encasement for physically protecting the IC and provides contact pads for coupling to the circuit board. In some applications, the packaged IC may be coupled to the circuit board via wire bonds or solder bumps.

One approach to IC packaging comprises a quad-flat no-leads (QFN) package. The OFM may provide some advantages, such as reduced lead inductance, a near chip scale footprint, thin profile, and low weight. Also, the QFN package typically includes perimeter I/O pads to ease circuit board trace routing, and the exposed copper die-pad technology offers enhanced thermal and electrical performance. QFN packaging may be well suited for applications where size, weight, and thermal and electrical performance are important.

Referring to FIG. 1, a typical QFN packaged electronic device 90 is now described. The electronic device 90 includes a plurality of leads 93 a-93 k, and a medially placed heat sink 91 adjacent thereto. The electronic device 90 includes an adhesive layer 96 on the heat sink 91, an IC 92 on the adhesive layer, and a plurality of wire bonds 97 a-97 k coupling the IC to the plurality of leads 93 a-93 k. The electronic device 90 also includes an encapsulation material 95 surrounding the IC 92, the plurality of wire bonds 97 a-97 k, and the plurality of leads 93 a-93 k. This electronic device 90 may have some drawbacks. In particular, the IC 92 includes a single row of band pads 81 a-81 k at a periphery thereof, thereby providing limited connections.

SUMMARY

An electronic device comprises a plurality of leads, and an IC comprising first and second pluralities of bond pads. The electronic device also includes an encapsulation material adjacent the plurality of leads and the IC so the plurality of leads extends to a bottom surface of the encapsulation material defining a first plurality of contact pads, a plurality of bond wires between the first plurality of bond pads and corresponding ones of the plurality of leads, and a plurality of conductors extending from corresponding ones of the second plurality of bond pads to the bottom surface of the encapsulation material defining a second plurality of contact pads. Advantageously, the electronic device may provide a QFN package with a mixed interconnect technique.

In particular, the first plurality of contact pads may be arranged around a periphery of the bottom surface of the encapsulation material. The second plurality of contact pads may be arranged on a medial portion of the bottom surface of the encapsulation material. The first plurality of bond pads may be arranged around a periphery of a top surface of the IC, and the second plurality of bond pads may be arranged on a medial portion of the top surface of the IC.

Also, the electronic device may further comprise a heat sink exposed on a top surface of the encapsulation material. The IC may be coupled to the heat sink. The first and second pluralities of bond pads may be on the top surface of the IC, and the IC may have a bottom surface coupled to the heat sink.

In some embodiments, each of the plurality of conductors may comprise an elongate conductor. In other embodiments, the plurality of conductors may comprise an interposer. The interposer may comprise a semiconductor substrate and a plurality of conductive vias extending therethrough. The plurality of conductors may further comprise a plurality of solder bodies between the second plurality of bond pads and the interposer. Each of the plurality of leads may have a sidewall exposed on a corresponding side of the encapsulation material.

Another aspect is directed to a method for making an electronic device. The method may comprise coupling a plurality of wire bonds between a first plurality of bond pads of an IC and corresponding ones of a plurality of leads, coupling a plurality of conductors to extend outwardly from a second plurality of bond pads of the IC, and forming an encapsulation material adjacent the plurality of leads and the IC so the plurality of leads extends to a bottom surface of the encapsulation material defining a first plurality of contact pads, and so that the plurality of conductors extends to the bottom surface defining a second plurality of contact pads.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of a cross sectional view of an electronic device, according to the prior art.

FIG. 2 is a schematic diagram of a cross sectional view of an electronic device, according to the present disclosure.

FIGS. 3A-3B are top and bottom plan views of the electronic device of FIG. 2.

FIGS. 4-5 are schematic diagrams of cross sectional views of other embodiments of the electronic device, according to the present disclosure.

FIGS. 6A-6E are schematic diagrams of cross sectional views of steps in a method for making the electronic device of FIG. 2.

FIGS. 7A-7D are schematic diagrams of cross sectional views of steps in a method for making the electronic device of FIG. 5.

DETAILED DESCRIPTION

The present embodiments will now be described more fully hereinafter with reference to the accompanying drawings, in which preferred embodiments of the present disclosure are shown. This present embodiments may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the present disclosure to those skilled in the art. Like numbers refer to like elements throughout, and prime and double prime notation are used to indicate similar elements in alternative embodiments.

Referring to FIGS. 2-3B, an electronic device 10 according to the present disclosure is now described. The electronic device 10 illustratively includes a plurality of leads 13 a-13 t, and an IC 12 positioned within the plurality of leads. The plurality of leads 13 a-13 t comprises an electrically conductive material, for example, copper or aluminum. The IC 12 illustratively includes first 21 a-21 k and second 18 a-18 e pluralities of bond pads (e.g. copper, aluminum). The first plurality of bond pads 21 a-21 k is arranged around a periphery of a top surface of the IC 12, and the second plurality of bond pads 18 a-18 e is arranged on a medial portion of the top surface of the IC.

The electronic device 10 also includes an encapsulation material 15 adjacent the plurality of leads 13 a-13 t and the IC 12. In particular, the encapsulation material 15 fills in the area between the leads 13 a-13 t, thereby surrounding the IC 12. As perhaps best seen in FIG. 3B, the encapsulation material 15 is formed so the plurality of leads 13 a-13 t extends to a bottom surface of the encapsulation material defining a first plurality of contact pads. The first plurality of contact pads are arranged around a periphery of the bottom surface of the encapsulation material 15. Each of the plurality of leads 13 a-13 t illustratively has a sidewall exposed on a corresponding side of the encapsulation material 15. Also, as perhaps best seen in FIG. 3A, the plurality of leads 13 a-13 t also extends to a top surface of the encapsulation material 15, thereby providing access to the first plurality of contact pads on either side of the electronic device 10.

The electronic device 10 includes a plurality of bond wires 17 a-17 k (e.g. copper, aluminum) between the first plurality of bond pads 21 a-21 k and corresponding ones of the plurality of leads 13 a-13 t, and a plurality of conductors 14 a-14 e extending from corresponding ones of the second plurality of bond pads 18 a-18 e to the bottom surface of the encapsulation material 15 defining a second plurality of contact pads. In the illustrated embodiment, each of the plurality of conductors 14 a-14 e comprises an elongate conductor, for example, an electrically conductive via made from copper or aluminum. The second plurality of contact pads are arranged on a medial portion of the bottom surface of the encapsulation material 15 (i.e. being within the first plurality of contact pads).

Also, the electronic device 10 illustratively includes a heat sink 11 exposed on a top surface of the encapsulation material 15. In the illustrated embodiment, the electronic device 10 includes a layer of thermally conductive adhesive material 16 between the heat sink 11 and the IC 12 for coupling the two together. As noted above, the first 21 a-21 k and second 18 a-18 e pluralities of bond pads may be on the top surface of the IC 12 while the bottom surface of the IC is coupled to the heat sink 11.

Referring now additionally to FIG. 4, another embodiment of the electronic device 10′ is now described. In this embodiment of the electronic device 10′, those elements already discussed above with respect to FIGS. 2-3B are given prime notation and most require no further discussion herein. This embodiment differs from the previous embodiment in that this electronic device 10′ has the plurality of conductors comprising an interposer 22′. The interposer 22′ illustratively includes a semiconductor substrate 23′, and a plurality of conductive vias 24 a′-24 e′ (e.g. copper, aluminum) extending therethrough. The interposer 22′ may be coupled to the second pluralities of bond pads 18 a-18 e using electrically conductive paste or reflow solder. Also, the semiconductor substrate 23′ may comprise a silicon substrate, an organic substrate, or a ceramic substrate.

Referring now additionally to FIG. 5, another embodiment of the electronic device 10″ is now described. In this embodiment of the electronic device 10″, those elements already discussed above with respect to FIGS. 2-3B are given double prime notation and most require no further discussion herein. This embodiment differs from the previous embodiment in that this electronic device 10″ has the plurality of conductors further comprising a plurality of solder bodies 25 a″-25 e″ between the second plurality of bond pads 18 a″-18 e″ and the interposer 22′.

Another aspect is directed to a method for making an electronic device 10. The method may comprise coupling a plurality of wire bonds 17 a-17 k between a first plurality of bond pads 21 a-21 k of an IC 12 and corresponding ones of a plurality of leads 13 a-13 t, coupling a plurality of conductors 14 a-14 e to extend outwardly from a second plurality of bond pads 18 a-18 e of the IC, and forming an encapsulation material 15 adjacent the plurality of leads and the IC so the plurality of leads extends to a bottom surface of the encapsulation material defining a first plurality of contact pads, and so that the plurality of conductors extends to the bottom surface defining a second plurality of contact pads.

Advantageously, the electronic device 10 may provide a QFN packaged device with a mixed interconnect technique, i.e. providing both wire bonds 17 a-17 k and electrically conductive vias 14 a-14 e for coupling to the IC 12. The electronic device 10 also provides multiple rows of contacts, which increase the die to package ratio. Moreover, the electronic device 10 is readily stackable and provides improved thermal performance over existing approaches.

Referring now additionally to FIGS. 6A-6E, a method for making the electronic device 10 of FIG. 2 is now described. In the illustrated embodiment, the method manufactures first and second electronic devices 10 a, 10 b (FIG. 6E), but it should be appreciated that via wafer level processing techniques, the method can be expanded for simultaneous manufacture of a large number of devices (i.e. much greater than the illustrated two). The method illustratively includes positioning stacks of the ICs 12 a-12 b, the heat sinks 11 a-11 b, and the adhesive material 16 a-16 b therebetween. The plurality of leads 113 a-113 c is positioned to surround the stacks. The method includes forming the pluralities of the wire bonds 17 aa-17 ka, 17 ab-17 kb between the ICs 12 a-12 b and the plurality of leads 113 a-113 c.

The method illustratively includes coupling a conductive frame 27 a-27 b (e.g. copper, aluminum) onto the respective stacks. In particular, the conductive frames 27 a-27 b each comprises a head portion, and a plurality of legs extending therefrom. The legs of the conductive frame 27 a-27 b are aligned with the second plurality of bond pads 18 aa-18 ea, 18 ab-18 eb for the first and second ICs 12 a-12 b. The method may include applying electrically conductive paste between the legs of the conductive frame 27 a-27 b and the second plurality of bond pads 18 aa-18 ea, 18 ab-18 eb. Helpfully, the head portion provides a readily graspable portion for aiding assembly, for example, using a pick-and-place machine.

The method illustratively includes forming the encapsulation material 15 to surround the stacks and the leads 113 a-113 c. The method illustratively includes grinding down a surface of the encapsulation material 15, which forms the lower surface of the electronic devices 10 a-10 b, so that the legs of the conductive frame 27 a-27 b remain (i.e. severing portions of the conductive frame 27 a-27 b to define the plurality of conductors 14 aa-14 ea, 14 ab-14 eb). The legs of the conductive frame 27 a-27 b define the plurality of conductors 14 aa-14 ea, 14 db-14 eb in the electronic devices 10 a-10 b. The method illustratively includes a singulation step where, for example, a blade cuts the piece along a midpoint of the leads 113 a-113 c.

Referring now additionally to FIGS. 7A-7D, a method for making the electronic device 10″ of FIG. 5 is now described. In the illustrated embodiment, the method manufactures first and second electronic devices 10 a″, 10 b″ (FIG. 7D), but it should be appreciated that via wafer level processing techniques, the method can be expanded for simultaneous manufacture of a large number of devices.

The method illustratively includes positioning the stacks of the ICs 12 a″-12 b″, the heat sinks 11 a″-11 b″, and the adhesive material 16 a″-16 b″ therebetween. The plurality of leads 113 a″-113 c″ is positioned to surround the stacks. The method includes forming the pluralities of the wire bonds 17 aa″-17 ka″, 17 ab″-17 kb″ between the ICs 12 a″-12 b″ and the plurality of leads 113 a″-113 c″. The method illustratively includes forming a plurality of solder bodies 25 aa″-25 ea″ 25 ab″-25 eb″ on the second plurality of bond pads 18 aa″-18 ea″, 18 ab″-18 eb″ of the ICs 12 a″-12 b″. The method also includes positioning the interposers 22 a″-22 b″ on the plurality of solder bodies 25 aa″-25 ea″, 25 ab″-25 eb″.

The method illustratively includes forming the encapsulation material 15″ to surround the stacks, the leads 113 a″-113 c″, and the interposers 22 a″-22 b″. The method illustratively includes a singulation step where a blade cuts the piece along the midpoint of the leads 113 a″-113 c″.

Many modifications and other embodiments of the present disclosure will come to the mind of one skilled in the art having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. Therefore, it is understood that the present embodiments are not to be limited to the specific embodiments disclosed, and that modifications and embodiments are intended to be included within the scope of the appended claims. 

That which is claimed is:
 1. An electronic device comprising: a plurality of leads; an integrated circuit (IC) comprising first and second pluralities of bond pads; an encapsulation material adjacent said plurality of leads and said IC so said plurality of leads extends to a bottom surface of said encapsulation material defining a first plurality of contact pads; a plurality of bond wires between said first plurality of bond pads and corresponding ones of said plurality of leads; and a plurality of conductors extending from corresponding ones of said second plurality of bond pads to the bottom surface of said encapsulation material defining a second plurality of contact pads.
 2. The electronic device of claim 1 wherein the first plurality of contact pads is arranged around a periphery of the bottom surface of said encapsulation material.
 3. The electronic device of claim 1 wherein the second plurality of contact pads is arranged on a medial portion of the bottom surface of said encapsulation material.
 4. The electronic device of claim 1 wherein said first plurality of bond pads are arranged around a periphery of a top surface of said IC; and wherein said second plurality of bond pads are arranged on a medial portion of the top surface of said IC.
 5. The electronic device of claim 1 further comprising a heat sink exposed on a top surface of said encapsulation material; and wherein said IC is coupled to said heat sink.
 6. The electronic device of claim 5 wherein said first and second pluralities of bond pads are on a top surface of said IC; and wherein said IC has a bottom surface coupled to said heat sink.
 7. The electronic device of claim 1 wherein each of said plurality of conductors comprises an elongate conductor.
 8. The electronic device of claim 1 wherein said plurality of conductors comprises an interposer.
 9. The electronic device of claim 8 wherein said interposer comprises a semiconductor substrate, and a plurality of conductive vias extending therethrough.
 10. The electronic device of claim 8 wherein said plurality of conductors further comprises a plurality of solder bodies between said second plurality of bond pads and said interposer.
 11. The electronic device of claim 1 wherein each of said plurality of leads has a sidewall exposed on a corresponding side of said encapsulation material.
 12. An electronic device comprising: a plurality of leads; an integrated circuit (IC) comprising first and second pluralities of bond pads; an encapsulation material adjacent said plurality of leads and said IC so said plurality of leads extends to a bottom surface of said encapsulation material defining a first plurality of contact pads arranged around a periphery of the bottom surface; a plurality of bond wires between said first plurality of bond pads and corresponding ones of said plurality of leads; and a plurality of conductors extending from said second plurality of bond pads to the bottom surface of said encapsulation material defining a second plurality of contact pads arranged within the plurality of first contact pads.
 13. The electronic device of claim 12 further comprising a heat sink exposed on a top surface of said encapsulation material; and wherein said IC is coupled to said heat sink.
 14. The electronic device of claim 12 wherein each of said plurality of conductors comprises an elongate conductor.
 15. The electronic device of claim 12 wherein said plurality of conductors comprises an interposer.
 16. The electronic device of claim 12 wherein each of said plurality of leads has a sidewall exposed on a corresponding side of said encapsulation material.
 17. A method for making an electronic device comprising: coupling a plurality of wire bonds between a first plurality of bond pads of an integrated circuit (IC) and corresponding ones of a plurality of leads; coupling a plurality of conductors to extend outwardly from a second plurality of bond pads of the IC; and forming an encapsulation material adjacent the plurality of leads and the IC so the plurality of leads extend to a bottom surface of the encapsulation material defining a first plurality of contact pads, and so that the plurality of conductors extends to the bottom surface defining a second plurality of contact pads.
 18. The method of claim 17 wherein the first plurality of contact pads is arranged around a periphery of the bottom surface of the encapsulation material.
 19. The method of claim 17 wherein the second plurality of contact pads is arranged on a medial portion of the top surface of the encapsulation material.
 20. The method of claim 17 further comprising positioning a heat sink to be coupled to the IC and exposed on a top surface of the encapsulation material.
 21. The method of claim 17 further comprising coupling a conductive frame to the second plurality of bond pads, and severing portions of the conductive frame to define the plurality of conductors.
 22. The method of claim 17 further comprising positioning an interposer to be coupled to the second plurality of bond pads to define the plurality of conductors.
 23. The method of claim 17 wherein the plurality of leads are initially part of a lead frame.
 24. The method of claim 17 further comprising exposing a sidewall of each of the plurality of leads on a corresponding side of the encapsulation material. 